Live Tiles would not drag down your system. To prove it, turn off all your Live Tile updates. Nothing will change.
Not to be disparaging, but your specs aren't the greatest. The oldest system that I've installed Windows 8 & 10 on is a Core 2 Q6600 which has a PassMark of over double your CPU. It runs Windows 8 & 10 fine. But you also have a 120GB Seagate, leading me to believe it's pretty slow too. Also, are the NVDIA drivers for your 7400 actually for Windows 8? I couldn't find a driver on their site for Windows 8, just for Windows 7.
But, ignoring the system limitations, check your drive's free space swap file settings and make sure you have enough room on your hard drive. In fact, go into your system properties and changing the swap file from System to a static size. Use the same value for both min & max. It will relieve Windows of the task to actively manage the size. Make sure you allocated the recommended size.
There could be other things as well, but that it may help.
As far as the tiles, I agree with the other people that recommend it. I strongly prefer the Start Screen rather than the Start Menu. I can find a program to run extremely fast in the Start Menu I organized. Much faster than using the Start Menu. And I don't need a lot of Desktop icons for my favorite programs. I just have them in the first part of my Start Screen. Even though I have an old 2-point touch screen installed, I use my mouse and the Start Screen saves me time everyday.
Like others said, give it a chance and approach it positively and not negatively and you should be happy with it.
Hope you can get your system to speed up.